/*

Change the definition of these macros to control the logging level statically

*/

macro_rules! log {

    (@ENDPT, $logger:expr, $($arg:tt)*) => {{

        // if let Some(w) = $logger.line_writer() {

        //     let _ = writeln!(w, $($arg)*);

        // }

    }};

    ($logger:expr, $($arg:tt)*) => {{

        // if let Some(w) = $logger.line_writer() {

        //     let _ = writeln!(w, $($arg)*);

        // }

    }};

}

use super::*;

use crate::common::*;

use core::ops::{Deref, DerefMut};

// Guard protecting an incrementally unfoldable slice of MapTempGuard elements

struct MapTempsGuard<'a, K, V>(&'a mut [HashMap<K, V>]);

// Type protecting a temporary map; At the start and end of the Guard's lifetime, self.0.is_empty() must be true

struct MapTempGuard<'a, K, V>(&'a mut HashMap<K, V>);

// Once the synchronous round has begun, this structure manages the

// native component's speculative branches, one per synchronous batch.

struct BranchingNative {

    branches: HashMap<Predicate, NativeBranch>,

}

// Corresponds to one of the native's synchronous batches during the synchronous round.

// ports marked for message receipt correspond to entries of

// (a) `gotten` if they have not received yet,

// (b) `to_get` if they have already received, with the given payload.

// The branch corresponds to a component solution IFF to_get is empty.

#[derive(Clone, Debug)]

struct NativeBranch {

    index: usize,

    gotten: HashMap<PortId, Payload>,

    to_get: HashSet<PortId>,

}

// Manages a protocol component's speculative branches for the duration

// of the synchronous round.

#[derive(Debug)]

struct BranchingProtoComponent {

    branches: HashMap<Predicate, ProtoComponentBranch>,

}

// One specualtive branch of a protocol component.

// `ended` IFF this branch has reached SyncBlocker::SyncBlockEnd before.

#[derive(Debug, Clone)]

struct ProtoComponentBranch {

    state: ComponentState,

    inner: ProtoComponentBranchInner,

    ended: bool,

}

// A structure wrapping a set of three pointers, making it impossible

// to miss that they are being setup for `cyclic_drain`.

struct CyclicDrainer<'a, K: Eq + Hash, V> {

    input: &'a mut HashMap<K, V>,

    inner: CyclicDrainerInner<'a, K, V>,

}

// Inner substructure of the Cyclic drainer to be passed through a callback function.

// See `CyclicDrainer::cyclic_drain`.

struct CyclicDrainerInner<'a, K: Eq + Hash, V> {

    swap: &'a mut HashMap<K, V>,

    output: &'a mut HashMap<K, V>,

}

// Small convenience trait for extending the stdlib's bool type with

// an optionlike replace method for increasing brevity.

trait ReplaceBoolTrue {

    fn replace_with_true(&mut self) -> bool;

}

//////////////// IMPL ////////////////////////////

impl ReplaceBoolTrue for bool {

    fn replace_with_true(&mut self) -> bool {

        let was = *self;

        *self = true;

        !was

    }

}

// CuUndecided provides a mostly immutable view into the ConnectorUnphased structure,

// making it harder to accidentally mutate its contents in a way that cannot be rolled back.

impl CuUndecided for ConnectorUnphased {

    fn logger_and_protocol_description(&mut self) -> (&mut dyn Logger, &ProtocolDescription) {

        (&mut *self.logger, &self.proto_description)

    }

    fn logger(&mut self) -> &mut dyn Logger {

        &mut *self.logger

    }

    fn proto_description(&self) -> &ProtocolDescription {

        &self.proto_description

    }

    fn native_component_id(&self) -> ComponentId {

        self.native_component_id

    }

}

impl<'a, K, V> MapTempsGuard<'a, K, V> {

    fn reborrow(&mut self) -> MapTempsGuard<'_, K, V> {

        MapTempsGuard(self.0)

    }

    fn split_first_mut(self) -> (MapTempGuard<'a, K, V>, MapTempsGuard<'a, K, V>) {

        let (head, tail) = self.0.split_first_mut().expect("Cache exhausted");

        (MapTempGuard::new(head), MapTempsGuard(tail))

    }

}

impl<'a, K, V> MapTempGuard<'a, K, V> {

    fn new(map: &'a mut HashMap<K, V>) -> Self {

        assert!(map.is_empty()); // sanity check

        Self(map)

    }

}

impl<'a, K, V> Drop for MapTempGuard<'a, K, V> {

    fn drop(&mut self) {

        assert!(self.0.is_empty()); // sanity check

    }

}

impl<'a, K, V> Deref for MapTempGuard<'a, K, V> {

    type Target = HashMap<K, V>;

    fn deref(&self) -> &<Self as Deref>::Target {

        self.0

    }

}

impl<'a, K, V> DerefMut for MapTempGuard<'a, K, V> {

    fn deref_mut(&mut self) -> &mut <Self as Deref>::Target {

        self.0

    }

}

impl Connector {

    /// Read the message received by the given port in the previous synchronous round.

    pub fn gotten(&self, port: PortId) -> Result<&Payload, GottenError> {

        use GottenError as Ge;

        if let ConnectorPhased::Communication(comm) = &self.phased {

            match &comm.round_result {

                Err(_) => Err(Ge::PreviousSyncFailed),

                Ok(None) => Err(Ge::NoPreviousRound),

                Ok(Some(round_ok)) => round_ok.gotten.get(&port).ok_or(Ge::PortDidntGet),

            }

        } else {

            return Err(Ge::NoPreviousRound);

        }

    }

    /// Creates a new, empty synchronous batch for the connector and selects it.

    /// Subsequent calls to `put` and `get` with populate the new batch with port operations.

    pub fn next_batch(&mut self) -> Result<usize, WrongStateError> {

        // returns index of new batch

        if let ConnectorPhased::Communication(comm) = &mut self.phased {

            comm.native_batches.push(Default::default());

            Ok(comm.native_batches.len() - 1)

        } else {

            Err(WrongStateError)

        }

    }

    fn port_op_access(

        &mut self,

        port: PortId,

        expect_polarity: Polarity,

    ) -> Result<&mut NativeBatch, PortOpError> {

        use PortOpError as Poe;

        let Self { unphased: cu, phased } = self;

        let info = cu.ips.port_info.map.get(&port).ok_or(Poe::UnknownPolarity)?;

        if info.owner != cu.native_component_id {

            return Err(Poe::PortUnavailable);

        }

        if info.polarity != expect_polarity {

            return Err(Poe::WrongPolarity);

        }

        match phased {

            ConnectorPhased::Setup { .. } => Err(Poe::NotConnected),

            ConnectorPhased::Communication(comm) => {

                let batch = comm.native_batches.last_mut().unwrap(); // length >= 1 is invariant

                Ok(batch)

            }

        }

    }

    /// Add a `put` operation to the connector's currently-selected synchronous batch.

    /// Returns an error if the given port is not owned by the native component,

    /// has the wrong polarity, or is already included in the batch.

    pub fn put(&mut self, port: PortId, payload: Payload) -> Result<(), PortOpError> {

        use PortOpError as Poe;

        let batch = self.port_op_access(port, Putter)?;

        if batch.to_put.contains_key(&port) {

            Err(Poe::MultipleOpsOnPort)

        } else {

            batch.to_put.insert(port, payload);

            Ok(())

        }

    }

    /// Add a `get` operation to the connector's currently-selected synchronous batch.

    /// Returns an error if the given port is not owned by the native component,

    /// has the wrong polarity, or is already included in the batch.

    pub fn get(&mut self, port: PortId) -> Result<(), PortOpError> {

        use PortOpError as Poe;

        let batch = self.port_op_access(port, Getter)?;

        if batch.to_get.insert(port) {

            Ok(())

        } else {

            Err(Poe::MultipleOpsOnPort)

        }

    }

    /// Participate in the completion of the next synchronous round, in which

    /// the native component will perform the set of prepared operations of exactly one

    /// of the synchronous batches. At the end of the procedure, the synchronous

    /// batches will be reset to a singleton set, whose only element is selected, and empty.

    /// The caller yields control over to the connector runtime to faciltiate the underlying

    /// coordination work until either (a) the round is completed with all components' states

    /// updated accordingly, (b) a distributed failure event resets all components'

    /// states to what they were prior to the sync call, or (c) the sync procedure encounters

    /// an unrecoverable error which ends the call early, and breaks the session and connector's

    /// states irreversably.

    /// Note that the (b) case necessitates the success of a distributed rollback procedure,

    /// which this component may initiate, but cannot guarantee will succeed in time or at all.

    /// consequently, the given timeout duration represents a duration in which the connector

    /// will make a best effort to fail the round and return control flow to the caller.

    pub fn sync(&mut self, timeout: Option<Duration>) -> Result<usize, SyncError> {

        // This method first destructures the connector, and checks for obvious

        // failure cases. The bulk of the behavior continues in `connected_sync`,

        // to minimize indentation, and enable convient ?-style short circuit syntax.

        let Self { unphased: cu, phased } = self;

        match phased {

            ConnectorPhased::Setup { .. } => Err(SyncError::NotConnected),

            ConnectorPhased::Communication(comm) => {

                match &comm.round_result {

                    Err(SyncError::Unrecoverable(e)) => {

                        log!(cu.logger(), "Attempted to start sync round, but previous error {:?} was unrecoverable!", e);

                        return Err(SyncError::Unrecoverable(e.clone()));

                    }

                    _ => {}

                }

                comm.round_result = Self::connected_sync(cu, comm, timeout);

                comm.round_index += 1;

                match &comm.round_result {

                    Ok(None) => unreachable!(),

                    Ok(Some(ok_result)) => Ok(ok_result.batch_index),

                    Err(sync_error) => Err(sync_error.clone()),

                }

            }

        }

    }

    // Attempts to complete the synchronous round for the given

    // communication-phased connector structure.

    // Modifies components and ports in `cu` IFF the round succeeds.

    #[inline]

    fn connected_sync(

        cu: &mut ConnectorUnphased,

        comm: &mut ConnectorCommunication,

        timeout: Option<Duration>,

    ) -> Result<Option<RoundEndedNative>, SyncError> {

        //////////////////////////////////

        use SyncError as Se;

        //////////////////////////////////

        // Create separate storages for ports and components stored in `cu`,

        // while kicking off the branching of components until the set of

        // components entering their synchronous block is finalized in `branching_proto_components`.

        // This is the last time cu's components and ports are accessed until the round is decided.

        let mut ips = cu.ips.clone();

        let mut branching_proto_components =

            HashMap::<ComponentId, BranchingProtoComponent>::default();

        let mut unrun_components: Vec<(ComponentId, ComponentState)> = cu

            .proto_components

            .iter()

            .map(|(&proto_id, proto)| (proto_id, proto.clone()))

            .collect();

        log!(cu.logger(), "Nonsync running {} proto components...", unrun_components.len());

        // initially, the set of components to run is the set of components stored by `cu`,

        // but they are eventually drained into `branching_proto_components`.

        // Some components exit first, and others are created and put into `unrun_components`.

        while let Some((proto_component_id, mut component)) = unrun_components.pop() {

            log!(

                cu.logger(),

                "Nonsync running proto component with ID {:?}. {} to go after this",

                proto_component_id,

                unrun_components.len()

            );

            let (logger, proto_description) = cu.logger_and_protocol_description();

            let mut ctx = NonsyncProtoContext {

                ips: &mut ips,

                logger,

                proto_component_id,

                unrun_components: &mut unrun_components,

            };

            let blocker = component.nonsync_run(&mut ctx, proto_description);

            log!(

                cu.logger(),

                "proto component {:?} ran to nonsync blocker {:?}",

                proto_component_id,

                &blocker

            );

            use NonsyncBlocker as B;

            match blocker {

                B::ComponentExit => drop(component),

                B::Inconsistent => return Err(Se::InconsistentProtoComponent(proto_component_id)),

                B::SyncBlockStart => assert!(branching_proto_components

                    .insert(proto_component_id, BranchingProtoComponent::initial(component))

                    .is_none()), // Some(_) returned IFF some component identifier key is overwritten (BAD!)

            }

        }

        log!(

            cu.logger(),

            "All {} proto components are now done with Nonsync phase",

            branching_proto_components.len(),

        );

        // Create temporary structures needed for the synchronous phase of the round

        let mut rctx = RoundCtx {

            ips, // already used previously, now moved into RoundCtx

            solution_storage: {

                let subtree_id_iter = {

                    // Create an iterator over the identifiers of this

                    // connector's childen in the _solution tree_.

                    // Namely, the native, all locally-managed components,

                    // and all this connector's children in the _consensus tree_ (other connectors).

                    let n = std::iter::once(SubtreeId::LocalComponent(cu.native_component_id));

                    let c = branching_proto_components

                        .keys()

                        .map(|&cid| SubtreeId::LocalComponent(cid));

                    let e = comm

                        .neighborhood

                        .children

                        .iter()

                        .map(|&index| SubtreeId::NetEndpoint { index });

                    n.chain(c).chain(e)

                };

                log!(

                    cu.logger,

                    "Children in subtree are: {:?}",

                    DebuggableIter(subtree_id_iter.clone())

                );

                SolutionStorage::new(subtree_id_iter)

            },

            spec_var_stream: cu.ips.id_manager.new_spec_var_stream(),

            payload_inbox: Default::default(), // buffer for in-memory payloads to be handled

            deadline: timeout.map(|to| Instant::now() + to),

        };

        log!(cu.logger(), "Round context structure initialized");

        // Prepare the branching native component, involving the conversion

        // of its synchronous batches (user provided) into speculative branches eagerly.

        // As a side effect, send all PUTs with the appropriate predicates.

        // Afterwards, each native component's speculative branch finds a local

        // solution the moment it's received all the messages it's awaiting.

        log!(

            cu.logger(),

            "Translating {} native batches into branches...",

            comm.native_batches.len()

        );

        // Allocate a single speculative variable to distinguish each native branch.

        // This enables native components to have distinct branches with identical

        // FIRING variables.

        let native_spec_var = rctx.spec_var_stream.next();

        log!(cu.logger(), "Native branch spec var is {:?}", native_spec_var);

        let mut branching_native = BranchingNative { branches: Default::default() };

        'native_branches: for ((native_branch, index), branch_spec_val) in

            comm.native_batches.drain(..).zip(0..).zip(SpecVal::iter_domain())

        {

            let NativeBatch { to_get, to_put } = native_branch;

            // compute the solution predicate to associate with this branch.

            let predicate = {

                let mut predicate = Predicate::default();

                // all firing ports have SpecVal::FIRING

                let firing_iter = to_get.iter().chain(to_put.keys()).copied();

                log!(

                    cu.logger(),

                    "New native with firing ports {:?}",

                    firing_iter.clone().collect::<Vec<_>>()

                );

                let firing_ports: HashSet<PortId> = firing_iter.clone().collect();

                for port in firing_iter {

                    let var = cu.ips.port_info.spec_var_for(port);

                    predicate.assigned.insert(var, SpecVal::FIRING);

                }

                // all silent ports have SpecVal::SILENT

                for port in cu.ips.port_info.ports_owned_by(cu.native_component_id) {

                    if firing_ports.contains(port) {

                        // this one is FIRING

                        continue;

                    }

                    let var = cu.ips.port_info.spec_var_for(*port);

                    if let Some(SpecVal::FIRING) = predicate.assigned.insert(var, SpecVal::SILENT) {

                        log!(&mut *cu.logger, "Native branch index={} contains internal inconsistency wrt. {:?}. Skipping", index, var);

                        continue 'native_branches;

                    }

                }

                // this branch is consistent. distinguish it with a unique var:val mapping and proceed

                predicate.inserted(native_spec_var, branch_spec_val)

            };

            log!(cu.logger(), "Native branch index={:?} has consistent {:?}", index, &predicate);

            // send all outgoing messages (by buffering them)

            for (putter, payload) in to_put {

                let msg = SendPayloadMsg { predicate: predicate.clone(), payload };

                log!(

                    cu.logger(),

                    "Native branch {} sending msg {:?} with putter {:?}",

                    index,

                    &msg,

                    putter

                );

                // sanity check

                assert_eq!(Putter, cu.ips.port_info.map.get(&putter).unwrap().polarity);

                rctx.putter_push(cu, putter, msg);

            }

            let branch = NativeBranch { index, gotten: Default::default(), to_get };

            if branch.is_ended() {

                // empty to_get set => already corresponds with a component solution

                log!(

                    cu.logger(),

                    "Native submitting solution for batch {} with {:?}",

                    index,

                    &predicate

                );

                rctx.solution_storage.submit_and_digest_subtree_solution(

                    cu,

                    SubtreeId::LocalComponent(cu.native_component_id),

                    predicate.clone(),

                );

            }

            if let Some(_) = branching_native.branches.insert(predicate, branch) {

                // thanks to the native_spec_var, each batch has a distinct predicate

                unreachable!()

            }

        }

        // restore the invariant: !native_batches.is_empty()

        comm.native_batches.push(Default::default());

        // Call to another big method; keep running this round

        // until a distributed decision is reached!

        log!(cu.logger(), "Searching for decision...");

        let decision = Self::sync_reach_decision(

            cu,

            comm,

            &mut branching_native,

            &mut branching_proto_components,

            &mut rctx,

        )?;

        log!(cu.logger(), "Committing to decision {:?}!", &decision);

        comm.endpoint_manager.udp_endpoints_round_end(&mut *cu.logger(), &decision)?;

        // propagate the decision to children

        let msg = Msg::CommMsg(CommMsg {

            round_index: comm.round_index,

            contents: CommMsgContents::CommCtrl(CommCtrlMsg::Announce {

                decision: decision.clone(),

            }),

        });

        log!(

            cu.logger(),

            "Announcing decision {:?} through child endpoints {:?}",

            &msg,

            &comm.neighborhood.children

        );

        for &child in comm.neighborhood.children.iter() {

            comm.endpoint_manager.send_to_comms(child, &msg)?;

        }

        let ret = match decision {

            Decision::Failure => {

                // untouched port/component fields of `cu` are NOT overwritten.

                // the result is a rollback.

                Err(Se::RoundFailure)

            }

            Decision::Success(predicate) => {

                // commit changes to component states

                cu.proto_components.clear();

                cu.proto_components.extend(

                    // "flatten" branching components, committing the speculation

                    // consistent with the predicate decided upon.

                    branching_proto_components

                        .into_iter()

                        .map(|(cid, bpc)| (cid, bpc.collapse_with(&predicate))),

                );

                // commit changes to ports and id_manager

                cu.ips = rctx.ips;

                log!(

                    cu.logger,

                    "End round with (updated) component states {:?}",

                    cu.proto_components.keys()

                );

                // consume native

                let round_ok = branching_native.collapse_with(&mut *cu.logger(), &predicate);

                Ok(Some(round_ok))

            }

        };

        log!(cu.logger(), "Sync round ending! Cleaning up");

        ret

    }

    // Once the synchronous round has been started, this procedure

    // routs and handles payloads, receives control messages from neighboring connectors,

    // checks for timeout, and aggregates solutions until a distributed decision is reached.

    // The decision is either a solution (success case), or a distributed timeout rollback (failure case)

    // The final possible outcome is an unrecoverable error, which results from some fundamental misbehavior,

    // a network channel breaking, etc.

    fn sync_reach_decision(

        cu: &mut impl CuUndecided,

        comm: &mut ConnectorCommunication,

        branching_native: &mut BranchingNative,

        branching_proto_components: &mut HashMap<ComponentId, BranchingProtoComponent>,

        rctx: &mut RoundCtx,

    ) -> Result<Decision, UnrecoverableSyncError> {

        // The round is in progress, and now its just a matter of arriving at a decision.

        let mut already_requested_failure = false;

        if branching_native.branches.is_empty() {

            // An unsatisfiable native is the easiest way to detect failure

            log!(cu.logger(), "Native starts with no branches! Failure!");

            match comm.neighborhood.parent {

                Some(parent) => {

                    if already_requested_failure.replace_with_true() {

                        Self::request_failure(cu, comm, parent)?

                    } else {

                        log!(cu.logger(), "Already requested failure");

                    }

                }

                None => {

                    log!(cu.logger(), "No parent. Deciding on failure");

                    return Ok(Decision::Failure);

                }

            }

        }

        // Create a small set of "workspace" hashmaps, to be passed by-reference into various calls.

        // This is an optimization, avoiding repeated allocation.

        let mut pcb_temps_owner = <[HashMap<Predicate, ProtoComponentBranch>; 3]>::default();

        let mut pcb_temps = MapTempsGuard(&mut pcb_temps_owner);

        let mut bn_temp_owner = <HashMap<Predicate, NativeBranch>>::default();

        // first, we run every protocol component to their sync blocker.

        // Afterwards we establish a loop invariant: no new decision can be reached

        // without handling messages in the buffer or arriving from the network

        log!(

            cu.logger(),

            "Running all {} proto components to their sync blocker...",

            branching_proto_components.len()

        );

        for (&proto_component_id, proto_component) in branching_proto_components.iter_mut() {

            let BranchingProtoComponent { branches } = proto_component;

            // must reborrow to constrain the lifetime of pcb_temps to inside the loop

            let (swap, pcb_temps) = pcb_temps.reborrow().split_first_mut();

            let (blocked, _pcb_temps) = pcb_temps.split_first_mut();

            // initially, no protocol components have .ended==true

            // drain from branches --> blocked

            let cd = CyclicDrainer::new(branches, swap.0, blocked.0);

            BranchingProtoComponent::drain_branches_to_blocked(cd, cu, rctx, proto_component_id)?;

            // swap the blocked branches back

            std::mem::swap(blocked.0, branches);

            if branches.is_empty() {

                log!(cu.logger(), "{:?} has become inconsistent!", proto_component_id);

                if let Some(parent) = comm.neighborhood.parent {

                    if already_requested_failure.replace_with_true() {

                        Self::request_failure(cu, comm, parent)?

                    } else {

                        log!(cu.logger(), "Already requested failure");

                    }

                } else {

                    log!(cu.logger(), "As the leader, deciding on timeout");

                    return Ok(Decision::Failure);

                }

            }

        }

        log!(cu.logger(), "All proto components are blocked");

        // ...invariant established!

        log!(cu.logger(), "Entering decision loop...");

        comm.endpoint_manager.undelay_all();

        'undecided: loop {

            // handle all buffered messages, sending them through endpoints / feeding them to components

            log!(cu.logger(), "Decision loop! have {} messages to recv", rctx.payload_inbox.len());

            while let Some((getter, send_payload_msg)) = rctx.getter_pop() {

                let getter_info = rctx.ips.port_info.map.get(&getter).unwrap();

                let cid = getter_info.owner; // the id of the component owning `getter` port

                assert_eq!(Getter, getter_info.polarity); // sanity check

                log!(

                    cu.logger(),

                    "Routing msg {:?} to {:?} via {:?}",

                    &send_payload_msg,

                    getter,

                    &getter_info.route

                );

                match getter_info.route {

                    Route::UdpEndpoint { index } => {

                        // this is a message sent over the network through a UDP endpoint

                        let udp_endpoint_ext =

                            &mut comm.endpoint_manager.udp_endpoint_store.endpoint_exts[index];

                        let SendPayloadMsg { predicate, payload } = send_payload_msg;

                        log!(cu.logger(), "Delivering to udp endpoint index={}", index);

                        // UDP mediator messages are buffered until the end of the round,

                        // because they are still speculative

                        udp_endpoint_ext.outgoing_payloads.insert(predicate, payload);

                    }

                    Route::NetEndpoint { index } => {

                        // this is a message sent over the network as a control message

                        let msg = Msg::CommMsg(CommMsg {

                            round_index: comm.round_index,

                            contents: CommMsgContents::SendPayload(send_payload_msg),

                        });

                        // actually send the message now

                        comm.endpoint_manager.send_to_comms(index, &msg)?;

                    }

                    Route::LocalComponent if cid == cu.native_component_id() => branching_native

                        .feed_msg(

                            cu,

                            rctx,

                            getter,

                            &send_payload_msg,

                            MapTempGuard::new(&mut bn_temp_owner),

                        ),

                    Route::LocalComponent => {

                        // some other component_id routed locally. must be a protocol component!

                        if let Some(branching_component) = branching_proto_components.get_mut(&cid)

                        {

                            // The recipient component is still running!

                            // Feed it this message AND run it again until all branches are blocked

                            branching_component.feed_msg(

                                cu,

                                rctx,

                                cid,

                                getter,

                                &send_payload_msg,

                                pcb_temps.reborrow(),

                            )?;

                            if branching_component.branches.is_empty() {

                                // A solution is impossible! this component has zero branches

                                // Initiate a rollback

                                log!(cu.logger(), "{:?} has become inconsistent!", cid);

                                if let Some(parent) = comm.neighborhood.parent {

                                    if already_requested_failure.replace_with_true() {

                                        Self::request_failure(cu, comm, parent)?

                                    } else {

                                        log!(cu.logger(), "Already requested failure");

                                    }

                                } else {

                                    log!(cu.logger(), "As the leader, deciding on timeout");

                                    return Ok(Decision::Failure);

                                }

                            }

                        } else {

                            // This case occurs when the component owning `getter` has exited,

                            // but the putter is still running (and sent this message).

                            // we drop the message on the floor, because it cannot be involved

                            // in a solution (requires sending a message over a dead channel!).

                            log!(

                                cu.logger(),

                                "Delivery to getter {:?} msg {:?} failed because {:?} isn't here",

                                getter,

                                &send_payload_msg,

                                cid

                            );

                        }

                    }

                }

            }

            // payload buffer is empty.

            // check if we have a solution yet

            log!(cu.logger(), "Check if we have any local decisions...");

            for solution in rctx.solution_storage.iter_new_local_make_old() {

                log!(cu.logger(), "New local decision with solution {:?}...", &solution);

                match comm.neighborhood.parent {

                    Some(parent) => {

                        // Always forward connector-local solutions to my parent

                        // AS they are moved from new->old in solution storage.

                        log!(cu.logger(), "Forwarding to my parent {:?}", parent);

                        let suggestion = Decision::Success(solution);

                        let msg = Msg::CommMsg(CommMsg {

                            round_index: comm.round_index,

                            contents: CommMsgContents::CommCtrl(CommCtrlMsg::Suggest {

                                suggestion,

                            }),

                        });

                        comm.endpoint_manager.send_to_comms(parent, &msg)?;

                    }

                    None => {

                        log!(cu.logger(), "No parent. Deciding on solution {:?}", &solution);

                        return Ok(Decision::Success(solution));

                    }

                }

            }

            // stuck! make progress by receiving a msg

            // try recv ONE message arriving through an endpoint

            log!(cu.logger(), "No decision yet. Let's recv an endpoint msg...");

            {

                // This is the first call that may block the thread!

                // Until a message arrives over the network, no new solutions are possible.

                let (net_index, comm_ctrl_msg): (usize, CommCtrlMsg) =

                    match comm.endpoint_manager.try_recv_any_comms(cu, rctx, comm.round_index)? {

                        CommRecvOk::NewControlMsg { net_index, msg } => (net_index, msg),

                        CommRecvOk::NewPayloadMsgs => {

                            // 1+ speculative payloads have been buffered

                            // but no other control messages that require further handling

                            // restart the loop to process the messages before blocking

                            continue 'undecided;

                        }

                        CommRecvOk::TimeoutWithoutNew => {

                            log!(cu.logger(), "Reached user-defined deadling without decision...");

                            if let Some(parent) = comm.neighborhood.parent {

                                if already_requested_failure.replace_with_true() {

                                    Self::request_failure(cu, comm, parent)?

                                } else {

                                    log!(cu.logger(), "Already requested failure");

                                }

                            } else {

                                log!(cu.logger(), "As the leader, deciding on timeout");

                                return Ok(Decision::Failure);

                            }

                            // disable future timeout events! our request for failure has been sent

                            // all we can do at this point is wait.

                            rctx.deadline = None;

                            continue 'undecided;

                        }

                    };

                // We received a control message that requires further action

                log!(

                    cu.logger(),

                    "Received from endpoint {} ctrl msg {:?}",

                    net_index,

                    &comm_ctrl_msg

                );

                match comm_ctrl_msg {

                    CommCtrlMsg::Suggest { suggestion } => {

                        // We receive the solution of another connector (part of the decision process)

                        // (only accept this through a child endpoint)

                        if comm.neighborhood.children.contains(&net_index) {

                            match suggestion {

                                Decision::Success(predicate) => {

                                    // child solution contributes to local solution

                                    log!(cu.logger(), "Child provided solution {:?}", &predicate);

                                    let subtree_id = SubtreeId::NetEndpoint { index: net_index };

                                    rctx.solution_storage.submit_and_digest_subtree_solution(

                                        cu, subtree_id, predicate,

                                    );

                                }

                                Decision::Failure => {

                                    // Someone timed out! propagate this to parent or decide

                                    match comm.neighborhood.parent {

                                        None => {

                                            log!(cu.logger(), "I decide on my child's failure");

                                            break 'undecided Ok(Decision::Failure);

                                        }

                                        Some(parent) => {

                                            log!(cu.logger(), "Forwarding failure through my parent endpoint {:?}", parent);

                                            if already_requested_failure.replace_with_true() {

                                                Self::request_failure(cu, comm, parent)?

                                            } else {

                                                log!(cu.logger(), "Already requested failure");

                                            }

                                        }

                                    }

                                }

                            }

                        } else {

                            // Unreachable if all connectors are playing by the rules.

                            // Silently ignored instead of causing panic to make the

                            // runtime more robust against network fuzz

                            log!(

                                cu.logger(),

                                "Discarding suggestion {:?} from non-child endpoint idx {:?}",

                                &suggestion,

                                net_index

                            );

                        }

                    }

                    CommCtrlMsg::Announce { decision } => {

                        // Apparently this round is over! A decision has been reached

                        if Some(net_index) == comm.neighborhood.parent {

                            // We accept the decision because it comes from our parent.

                            // end this loop, and and the synchronous round

                            return Ok(decision);

                        } else {

                            // Again, unreachable if all connectors are playing by the rules

                            log!(

                                cu.logger(),

                                "Discarding announcement {:?} from non-parent endpoint idx {:?}",

                                &decision,

                                net_index

                            );

                        }

                    }

                }

            }

            log!(cu.logger(), "Endpoint msg recv done");

        }

    }

    // Send a failure request to my parent in the consensus tree

    fn request_failure(

        cu: &mut impl CuUndecided,

        comm: &mut ConnectorCommunication,

        parent: usize,

    ) -> Result<(), UnrecoverableSyncError> {

        log!(cu.logger(), "Forwarding to my parent {:?}", parent);

        let suggestion = Decision::Failure;

        let msg = Msg::CommMsg(CommMsg {

            round_index: comm.round_index,

            contents: CommMsgContents::CommCtrl(CommCtrlMsg::Suggest { suggestion }),

        });

        comm.endpoint_manager.send_to_comms(parent, &msg)

    }

}

impl NativeBranch {

    fn is_ended(&self) -> bool {

        self.to_get.is_empty()

    }

}

impl BranchingNative {

    // Feed the given payload to the native component

    // May result in discovering new component solutions,

    // or fork speculative branches if the message's predicate

    // is MORE SPECIFIC than the branches of the native

    fn feed_msg(

        &mut self,

        cu: &mut impl CuUndecided,

        rctx: &mut RoundCtx,

        getter: PortId,

        send_payload_msg: &SendPayloadMsg,

        bn_temp: MapTempGuard<'_, Predicate, NativeBranch>,

    ) {

        log!(cu.logger(), "feeding native getter {:?} {:?}", getter, &send_payload_msg);

        assert_eq!(Getter, rctx.ips.port_info.map.get(&getter).unwrap().polarity);

        let mut draining = bn_temp;

        let finished = &mut self.branches;

        std::mem::swap(draining.0, finished);

        // Visit all native's branches, and feed those whose current predicates are

        // consistent with that of the received message.

        for (predicate, mut branch) in draining.drain() {

            log!(cu.logger(), "visiting native branch {:?} with {:?}", &branch, &predicate);

            let var = rctx.ips.port_info.spec_var_for(getter);

            if predicate.query(var) != Some(SpecVal::FIRING) {

                // optimization. Don't bother trying this branch,

                // because the resulting branch would have an inconsistent predicate.

                // the existing branch asserts the getter port is SILENT

                log!(